Method and system of CDMA communication

1. A method of CDMA communication, in which page messages are transmitted over paging channels to mobile stations, comprising the steps of: providing a page message notice channel that is different from the paging channels; generating a page message notice signal indicating whether a monitor-required page message is included in an up-coming time slot, the up-coming time slot being transmitted certain slots later than the current time slot; and transmitting the page message notice signal over the page message notice channel., wherein the page message notice signal has a plurality of information bits for each paging channel, the plurality of information bits including a first information bit that indicates whether a monitor-required page message is included in the up-coming time slot addressed to at least one mobile station in a first ID class, and a second information bit that indicates whether a monitor-required page message is included in the up-coming time slot addressed to at least one mobile station in a second ID class, and wherein the first and second ID classes correspond to CLASS 0 and CLASS 1 for an IMSI (International Mobile Station Identity).

2. The method according to claim 1 , further comprising the steps of: monitoring the page message notice channel by each mobile station; and monitoring the paging channel by a particular one of the mobile stations only when the page message notice signal indicates that the up-coming time slot includes a monitor-required page message addressed to the particular one of the mobile stations.

3. The method according to claim 1 , further comprising the step of: performing interleave processing on the page message notice signal.

4. A method of CDMA communication, in which page messages are transmitted over paging channels to mobile stations having ID numbers, comprising the steps of: providing a page message notice channel that is different from the paging channels; generating a page message notice signal based on at least a part of the ID numbers of the mobile stations, the page message notice signal indicating whether a monitor-required page message is included in an up-coming time slot, the up-coming time slot being transmitted certain slots later than the current time slot; and transmitting the page message notice signal over the page message notice channel, wherein the page message notice signal comprises a seven-bit code of IMSI 11 12 used for an IMSI (International Mobile Station Identity), and one information bit indicating whether a page message is included in the up-coming time slot assigned to at least one mobile station, wherein the one information bit is set to zero and the seven-bit code is set to a random number from 00 to 99 when no message is addressed to any of the mobile stations, to which the same paging channel is assigned, wherein the one information bit is set to one and the even-bit code is set to the ID number of the mobile station when a message is addressed to one of the mobile stations, to which the same paging channel is assigned, and wherein the one information bit is set to one and the seven-bit code is set to one of twenty-eight numbers that are different from 00 to 99 when messages are addressed to plural mobile stations to which the same paging channel is assigned.

5. The method according to claim 4 , further comprising the step of: performing interleave processing on the page message notice signal.

6. A CDMA communication system, comprising: a base station which includes a page message generator that generates page messages for transmission over a plurality of paging channels, and a notice signal generator that generates a page message notice signal for transmission over a page message notice channel that is different from the paging channels, the page message notice signal indicating whether a monitor-required page message is included in an up-coming time slot transmitted N slots later than the current time slot; and mobile stations, each of which monitors the page message notice channel, and monitors a certain assigned paging channel only when the page message notice signal indicates that a monitor-required page message is included in the up-coming time slot assigned to the mobile station, wherein the page message notice signal has a plurality of information bits for each paging channel, the plurality of information bits including a first information bit that indicates whether a monitor-required page message is included in the up-coming time slot addressed to at least one mobile station in a first ID class, and a second information bit that indicates whether a monitor-required page message is included in the up-coming time slot addressed to at least one mobile station in a second ID class, and wherein the first and second ID classes correspond to CLASS 0 and CLASS 1 for an IMSI (International Mobile Station Identity).

7. The CDMA communication system according to claim 6 , wherein each of the mobile stations comprises a CPU which processes the page message; a baseband-processing unit which processes the page message notice signal; and a control circuit which controls the CPU and the baseband-processing unit.

8. The CDMA communication system according to claim 7 , wherein the control circuit controls the CPU so that the CPU does not wake up for operation until the page message notice signal indicates that a monitor-required page message is included in the up-coming time slot assigned to the mobile station.

9. The CDMA communication system according to claim 6 , wherein the base station comprises an interleave circuit which interleaves the page message notice signal to be transmitted.

10. A CDMA communication system, comprising: a base station which transmits page message over a plurality of paging channels, and a page message notice signal over a page message notice channel that is different from the paging channels, the page message notice signal indicating whether a monitor-required page message is included in an up-coming time slot transmitted N slots later than the current time slot; and mobile stations, each of which monitors the page message notice channel, and monitors a certain assigned paging channel only when the page message notice signal indicates that a monitor-required page message is included in the up-coming time slot assigned to the mobile station, wherein the mobile stations have ID numbers, and the base station generates the page message notice signal based on at least a part of the ID numbers of the mobile stations, wherein the page message notice signal comprises a seven-bit code of IMSI-11-12 used for an INMSI (International Mobile Station Identity), and one information bit indicating whether a page message is included in the up-coming time slot assigned to at least one mobile station, wherein the one information bit is set to zero and the seven-bit code is set to a random number from 00 to 99 when no message is addressed to any of the mobile stations, to which the same paging channel is assigned, wherein the one information bit is set to one and the seven-bit code is set to the ID number of the mobile station when a message is addressed to one of the mobile stations, to which the same paging channel is assigned, and wherein the one information bit is set to one and the seven-bit code is set to one of twenty-eight numbers that are different from 00 to 99 when messages are addressed to plural mobile stations to which the same paging channel is assigned.

11. The CDMA communication system according to claim 10 , wherein the base station comprises an interleave circuit which interleaves the page message notice signal to be transmitted.

12. The CDMA communication system according to claim 10 , wherein each of the mobile stations comprises: a CPU which processes the page message; a baseband-processing unit which processes the page message notice signal; and a control circuit which controls the CPU and the baseband-processing unit.

13. The CDMA communication system according to claim 12 , wherein the control circuit controls the CPU so that the CPU does not wake up for operation until the page message notice signal indicates that a monitor-required page message is included in the up-coming time slot assigned to the mobile station.

14. A method of CDMA communication, in which page messages are transmitted over a paging channel to mobile stations which are assigned to the paging channel and which have ID numbers, comprising the steps of: providing a page message notice channel that is different from the paging channels; generating a page message notice signal indicating whether a monitor-required page message is included in an up-coming time slot, the up-coming time slot being transmitted at least one slot later than a current time slot, and transmitting the page message notice signal over the page message notice channel, wherein the page message notice signal comprises a seven-bit code and an information bit, and wherein the information bit is set to a value indicating whether the seven-bit code identifies the ID number of a particular mobile station to which a message is addressed if only one message is to be transmitted, or whether the seven-bit code specifies either that no messages are present for any of the mobile station or that messages are present for transmission to more than one of the mobile stations.

15. The method of claim 14 , wherein the information bit is set to zero and the seven-bit code is set to a value in a first predetermined range if no messages are present for any of the mobile stations, the information bit is set to one and the seven-bit code is set to a value that identifies the particular mobile station if only one message is to be transmitted, and the information bit is set to one and the seven-bit code is set to a value in a second predetermined range if messages are present for transmission to more than one of the mobile stations.

16. The method of claim 15 , wherein the first predetermined range is 99 or less and the second predetermined range is greater than 99 .